Abstract
Two genes encoding Arabidopsis (Arabidopsis thaliana) DEAD-box RNA helicases were identified in a functional genomics screen as being down-regulated by multiple abiotic stresses. Mutations in either gene caused increased tolerance to salt, osmotic, and heat stresses, suggesting that the helicases suppress responses to abiotic stress. The genes were therefore designated STRESS RESPONSE SUPPRESSOR1 (STRS1; At1g31970) and STRS2 (At5g08620). In the strs mutants, salt, osmotic, and cold stresses induced enhanced expression of genes encoding the transcriptional activators DREB1A/CBF3 and DREB2A and a downstream DREB target gene, RD29A. Under heat stress, the strs mutants exhibited enhanced expression of the heat shock transcription factor genes, HSF4 and HSF7, and the downstream gene HEAT SHOCK PROTEIN101. Germination of mutant seed was hyposensitive to the phytohormone abscisic acid (ABA), but mutants showed up-regulated expression of genes encoding ABA-dependent stress-responsive transcriptional activators and their downstream targets. In wild-type plants, STRS1 and STRS2 expression was rapidly down-regulated by salt, osmotic, and heat stress, but not cold stress. STRS expression was also reduced by ABA, but salt stress led to reduced STRS expression in both wild-type and ABA-deficient mutant plants. Taken together, our results suggest that STRS1 and STRS2 attenuate the expression of stress-responsive transcriptional activators and function in ABA-dependent and ABA-independent abiotic stress signaling networks.
Highlights
The hidden nature of causality is a puzzling, yet critical notion for effective decision-making
To analyze the spectrum of causal interactions, both transparent and opaque in complex systems, we introduce in this article a method that is based on interactions of symbolic dynamics [17] in reconstructed attractors [18]
We quantify the nature of causality among time series by gauging the correspondence of patterns in contemporaneously embedded neighborhoods and the detection and quantification of dark causality
Summary
Encountered in the trading activity during financial crises and market crashes when investors are more pessimistic [25]. By calculating PC, we expose the hidden interaction between the two prey types (Fig. 2F), a relationship whose meaning is neither positive nor negative and falls into the category of dark causality. In finance, such relationships cannot be defined as beneficial or detrimental (as they can in ecology), but in the CDS example they are abundant and need to be further scrutinized. The asymmetrical domination of dark causality means that the CDS market is strongly interconnected yet the correspondences in the shadow attractors are not clear about similar or opposite temporal patterns. The preeminence of dark causality can be seen as a sign of “terra incognita” (in Latin for unexplored land) in the already notorious CDS market [30]
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